Some tests for secondary batteries include screening (self-discharge test) for eliminating the self-discharge defect of the secondary battery. For example, as disclosed in Patent Literature 1, it has been known that screening is performed in a pressed state, whereby the micro short-circuiting can be found in a short period of time.
Moreover, as disclosed in Patent Literature 2, it has been known that aging is performed while pressure is applied in order to find the micro short-circuiting in a secondary battery in a short period of time.